The present invention relates in general to inflatable air bag safety restraints, and, more specifically, to a side air bag deployable from within a passenger seat.
Vehicular air bags protect vehicle occupants during a crash event such as a rollover or a collision with a pole or another vehicle. Historically, air bags were initially provided in the steering wheel and on the instrument panel ahead of the front seat passenger for protection during front end collisions. More recently, side impact air bags have been developed which deploy between an occupant and a side of the vehicle (e.g., a door, B-pillar, or a side window). One type of air bag is mounted internally within a passenger seat and is configured to quickly emerge from the seat into the space between the passenger and the side of the vehicle. Such a seat-mounted air bag may use the expansion of the inflating air bag within the seat to rupture or tear a seam in a seat covering to allow the air bag to project into the desired space.
It is very challenging to deploy a side air bag into the gap between the passenger and the inside surface of the vehicle side (e.g., door) quickly enough 1) because of the smaller initial space between the passenger and the side of the vehicle and 2) because there is less crush space at the side of the vehicle so that impingement of the side structure into the gap occurs sooner in a crash event. Bag inflation must be sufficiently energetic to rupture the seam of the seat covering and to get in place rapidly. Therefore, a relatively higher inflation pressure and gas flow rate must be used. Due to the higher forces, however, it becomes more difficult to ensure that bag expansion is properly channeled in the desired directions. For example, the natural tendency of an inflating bag to expand in all directions may be undesirable in the case of a seat-mounted air bag because it is critical for a tear seam in the seat cover to rupture early in the expansion of the air bag so that the air bag is able to expand into the desired area for protecting the passenger (i.e., instead of encroaching into other areas within the seat or undesirably bulging the seat). Prior art seat-mounted side air bags have employed various supplemental structures in order to direct the forces and the direction of air bag expansion toward the tear seam by using a deployment chute, a plastic clam shell housing, force concentrator straps, seat foam reinforcements, and other supplemental structures. It would be desirable to ensure air bag expansion in the necessary direction without the added expense of such additional structures.